Eli Turkel writes, inter alia, "I always enjoy reading from the 
sefer of R. Eider where after giving the large shiur states that this 
is "defined" as normal eating since eating abnormally invalidates the 
mitzvah. I dont understand how one can define as normal eating 
filling ones mouth with matzah and then slowly chewing it and then
finaly swallowing it within 2 minutes is normal."

     There is no one, to the best of my knowledge, who requires 
eating "maximum" kezaysim in the smallest shiur of k'dei achilas 
pras.  These are two contradictory chumros.  Since a pras is either 3 
or four zeisim, the bigger the kazayis, the bigger the k'dei achilas 
pras.  Thus, the matzo can be eaten at a normal pace; the machmirim 
should eat for a longer period of time, until they complete their 
shiur.

EMT